Atomic Structure and the Periodic Table

Question 1

proton

Answer 1

positively charged particle found in the nucleus of an atom
relative mass:1
charge:+1

Question 2

neutron

Answer 2

particle with zero charge found in the centre of the atom
relative mass:1
charge:0

Question 3

electron

Answer 3

negatively charged particles found on energy levels (shells) surrounding the nucleus inside atoms
relative mass: very small
charge:-1
-move around nucleus in electron shells
-negatively charged + small, but cover a lot of space
-the volume of their orbits determines the size of the atom
-virtually no mass

Question 4

in an ATOM
number of protons =

Answer 4

number of electrons
-charges cancel out
-atoms are neutral (no charge overall)

Question 5

mass number

Answer 5

top number
-mass of element
-total number of protons and neutrons in the atom

Question 6

atomic number

Answer 6

bottom number
-number protons in an atom (therefore number of electrons)

Question 7

element

Answer 7

a substance made up of atoms that all have the same number of protons in their nucleus

a substance containing only one type of atom

Question 8

isotopes

Answer 8

atoms of the same element with the same number of protons but a different number of neutrons
(same atomic number but different mass numbers)

Question 9

compound

Answer 9

two or more elements chemically bonded in fixed proportions

Question 10

diatomic

Answer 10

travels rounds as a pair of atoms

Question 11

relative atomic mass (Ar)=

Answer 11

relative atomic mass (Ar)=sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes

The average mass of atoms on an element taking into account the mass and amount of each isotope it contains

Question 12

nucleus

Answer 12

central part of the atom containing protons and neutrons
-in the middle of the atom
-contains protons and neutrons
-positive charge due to the protons
-almost the whole mass of the atom is concentrated in the nucleus

Question 13

ions

Answer 13

An electrically charged particle containing different numbers of protons and electrons
number of protons ≠ number of electrons
-it has an overall charge

Question 14

atom

Answer 14

a particle with no electrical charge made up of a nucleus combining protons and neutrons and surrounded by electrons

Question 15

energy level (shell)

Answer 15

the region an electron occupies surrounding the nucleus inside an atom
in most atoms, the outer shell is not full and this makes the atom want to react to fill it

Question 16

electronic structure

Answer 16

the arrangement of electrons in the energy levels of an atom

Question 17

group

Answer 17

the name given to each column in the periodic table

Question 18

period

Answer 18

the name given to a row in the periodic table

Question 19

alkali metals

Answer 19

the elements in group 1 of the periodic table

Question 20

noble gases

Answer 20

the elements in group 0 of the periodic table

Question 21

halogens

Answer 21

the elements in group 7 of the periodic table

Question 22

halides

Answer 22

compounds made from group 7 elements

Question 23

mixture

Answer 23

more than one substance that are not chemically bonded

Question 24

solvent

Answer 24

the liquid that a solute dissolves in

Question 25

solution

Answer 25

a solute dissolved in a solvent

Question 26

soluble

Answer 26

a substance that will dissolve

Question 27

insoluble

Answer 27

a substance that will not dissolve

Question 28

solute

Answer 28

the solid that dissolves in a solvent

Question 29

filtration

Answer 29

separates insoluble solids from liquids

Question 30

evaporation

Answer 30

separate soluble solids from solutions
-pour solution into evaporating dish
-slows heat the solution - the solvent will evaporate and the solution will get more concentrated. eventually crystals will start to form.
- keep heating the evaporating dish until all you have left are dry crystals

can only be used if the salt doesn’t decompose (break down) when heated

Question 31

crystallisation

Answer 31

separate soluble solids from solutions
- pour solution into evaporating dish and gently heat - some of the solvent will evaporate and the solution will get more concentrated
-once some of the solvent has evaporated or you see crystals start to form, remove the dish from the heat and leave the solution to cool
-the salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution
-filter the crystals out of the solution and leave them in a warm place to dry

Question 32

history of the atom

Answer 32

solid spheres
plum pudding model
nuclear model - Rutherford (alpha particle scattering experiment)
nuclear model - Bohr
Rutherford - existence of protons
James Chadwick - existence of neutrons - model of the atom close to nowadays nuclear model

Question 33

plum pudding model

Answer 33

J J Thomson
ball of positive charge with electrons stuck in it

Question 34

nuclear model

Answer 34

Rutherford
tiny, positively charged nucleus at the centre, where most of the mass is concentrated. A ‘cloud’ of negative electrons surround the nucleus - most of the atom is empty space
-conducted alpha particle scattering experiments
-fired positively charged alpha particles at an extremely thin sheet of gold-expected to pass straight through the sheet or be slightly deflected at most
-when alpha particles came near the concentrated, positive charge of the nucleus, they were deflected
- if they were fired directly at the nucleus, they were deflected backwards
-otherwise, they passed through the empty space

Question 35

Bohr’s nuclear model

Answer 35

scientists realised that electrons in a ‘cloud’ around the nucleus of an atom, as Rutherford described, would be attracted to the nucleus, causing the atom to collapse

suggested that all electrons were contained in shells
- electrons orbit the nucleus in fixed shells and aren’t anywhere in between
- each shell is a fixed distance from the nucleus

Question 36

methods mixtures can be separated

Answer 36

chromatography
filtration
crystallisation
simple distillation
fractional distillation

Question 37

simple distillation

Answer 37

used to separate a liquid from a solution
-solution is heated, part with lowest boiling point evaporates first
-vapour is cooled, condenses, and is collected
-rest of solution is left behind in the flask

can be used to separate salt and sea water
problem is can only be used to separate things with very different boiling points - if the temperature goes higher than the boiling point of the substance with the higher boiling point, they’ll mix again

Question 38

fractional distillation

Answer 38

used to separate a mixture of liquids
-put mixture in flask and stick a fractionating column on top and heat it
-the different liquids have different boiling points - evaporate at different temps
-liquid with lowest boiling point evaporates first - when the temp on the thermometer matches the boiling point, it will reach the top of the column
-liquids with higher boiling points will start to evaporate, but the column gets cooler towards the top so will only get part of the way before condensing and running back towards the flask
-when the first liquid has been collected, you raise the temperature until the next one reaches the top

Question 39

chromatography

Answer 39

used to separate different dyes in ink
-draw a line in pencil (insoluble and won’t dissolve in the solvent) near the bottom of a sheet of filter paper
-add a spot of ink to the line and place the sheet in a beaker of solvent e.g. water
-make sure your ink isn’t touching the solvent otherwise is may dissolve
-put a lid on top of the contained to prevent it from evaporating
-solvent seeps into the paper, carrying the ink with it
-each different dye in the ink will move up the paper at a different rate so will separate out + each will form a spot in a different place
-if any of the dye’s are insoluble they will stay on the baseline
-when the solvent has nearly reached the top of the paper, take the paper out of the beaker and leave it to dry
-the end result is a pattern of spots called a chromatogram

Question 40

how was the periodic table previously categorised

Answer 40

their physical and chemical properties
their relative atomic mass

Question 41

how did Dmitri Mendeleev order the periodic table

Answer 41

left gaps and predicted new elements
-mainly in order of atomic mass but switched that order if the properties meant it should be changed
-organised elements with similar properties into the same group
-gaps were left to make sure that elements with similar properties stayed in the same groups. some indicated undiscovered elements + allowed Mendeleev to predict what their properties might be

discovery of isotopes supported this - to not place elements in a strict order of atomic mass but to take account of their properties - isotopes of the same element have different atomic masses but the same chemical properties so occupy the same position on the periodic table

Question 42

modern periodic table

Answer 42

100ish elements
elements laid out in order of increasing atomic (proton) number - arranging the elements like this means there are repeating patterns in the properties of the elements
metals - left
non-metals - right
vertical columns - groups. group number tells you how many electrons are in the outer shell
rows - periods-each new period represents another full shell of electrons

Question 43

metals

Answer 43

elements which can form positive ions when they react
towards the bottom and left of the periodic table
left - don’t have many electrons to remove
bottom - have outer electrons which are a long way from the nucleus so feel a weaker attraction
BOTH of these mean that not much energy is needed to remove the electrons

metallic bonding - have similar basic physical properties
-strong
-malleable
-great conductors of heat and electricity
-high melting and boiling points

Question 44

non-metals

Answer 44

don’t generally from positive ions when they react
at far right and top of periodic table
forming positive ions is much more difficult
right - lots of electrons to remove to get a full outer shell
top - outer electrons are close to the nucleus so feel a strong attraction
far more feasible for them to gain or share electrons to get a full outer shell

no metallic bonding
-dull looking
-brittle
-aren’t always solids at room temp
-don’t generally conduct electricity
-lower density

Question 45

transition metals

Answer 45

between group 2 and 3
centre of the periodic table
-typical metals and have the expected properties of metals
-they also have:
-can have more than one ion
-transition metal ions are often coloured
-transition metal compounds make good catalysts

Question 46

group 1 elements

Answer 46

the Alkali metals - reactive, soft metals
one electron in outer shell - very reactive + gives them similar properties
- low density
trends as you go DOWN the group:
increasing reactivity - outer electron is more easily lost as the attraction between the nucleus and electron decreases, because the electron is further away from the nucleus the further down the group you go
lower melting and boiling points
higher relative atomic mass

only ever react to form ionic compounds with non-metals (transfer of electrons)
need little energy to lose an electron and form 1+ ions

more reactive than transition metals - more vigorous
- much less dense, strong, and hard than transition metals + have lower boiling points

Question 47

alkali metals reaction with water

Answer 47

when Group 1 metals are put in water, they react vigorously to produce hydrogen gas and metal hydroxides - compounds that dissolve in water to produce alkaline solutions
2Na (s) + 2H 2 O (l) → 2NaOH (aq) + H 2 (g)
sodium + water → sodium hydroxide + hydrogen
- the more reactive (lower down the group), the more violent the reaction
- amount of energy released by the reaction increases down the group

Question 48

alkali metals reaction with chlorine

Answer 48

Group 1 metals react vigorously when heated in chlorine gas to form white metal chloride salts
as you go down the group, reactivity increases so the reaction with chlorine gets more vigorous

Question 49

alkali metals reaction with oxygen

Answer 49

form a metal oxide
- different types will form depending on the Group 1 metal
Lithium → lithium oxide
Sodium → mixture of sodium oxide and sodium peroxide
Potassium → mixture of potassium peroxide and potassium superoxide

Question 50

group 7 elements

Answer 50

Halogens
non-metals with coloured vapours
as you go DOWN the group:
-become less reactive - it’s harder to gain an extra electron, because the outer shell’s further from the nucleus
- have higher melting and boiling points
- have higher relative atomic masses

can form molecular compounds - can share electrons with other non-metals via covalent bonding to achieve a full outer shell

form ionic bonds with metals - 1- ions called halides when they bond with metals

more reactive halogens will displace less reactive ones (displacement reaction)

Question 51

group 0 elements

Answer 51

the Noble Gases - inert, colourless gases
eight electrons in outer shell (except helium which has 2) - full outer shell
- stable - don’t react with much at all
exist as monatomic gases - single atoms not bonded to each other
non-flammable

as you go DOWN the group:
-boiling point increases - greater number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome